Feature request: @devcontainers/cli as a docker CLI plugin

[trxcllnt]

We've found it difficult to on-board users accustomed to the docker CLI to @devcontainers/cli.

It would be awesome if @devcontainers/cli were a docker CLI front-end plugin, similar to docker compose, docker buildx, etc.

Partially the motivation is similar to existing issues/PRs -- having a way to use the CLI without node would be great:

• Package standalone binaries via @vercel/pkg #343
• Problems with packaging and distribution of devcontainer as standalone executable #614
• RFC: Build as single executable application #618

This would also hopefully provide incentive to better align with docker CLI idioms. For example:

• The docker CLI has docker build, and Buildx/compose have docker buildx build and docker compose build.
• The docker CLI has docker run, and compose has docker compose run.
• etc.

For example, in the absence of devcontainer run <args>, we find ourselves writing scripts to wrap @devcontainers/cli and mimic the behavior:

local container_id rm up_args exec_args;

_parse_args_somehow rm up_args exec_args;

on_exit() {
    local code=$?;
    if test -n "${rm-}" && test -n "${container_id-}"; then
        docker rm -f "${container_id}" >/dev/null 2>&1 || true;
        container_id="";
    fi
    exit "${code}";
}

trap on_exit EXIT;

container_id="$(devcontainer up ${rm:+--remove-existing-container} "${up_args[@]}" | jq -r '.containerId')";

devcontainer exec --workspace-folder . --config <path> "${exec_args[@]}";

It would be really neat to type docker devcontainer build . or docker devcontainer run --rm -it ..., especially if the @devcontainers/cli plugin also shipped shell completions!